Roll coating machine



P 1935- w. J. MONTGOMERY ROLL COATING MACHINE 2 Sheefs-She'er, 1

Filed July 25, 1932 Sept. 24, 1935.

W. J MONTGOMERY ROLL COATING MACHINE 2 Sheets-Shet 2 Filed July 25, 19323 Wu am bo'b u illiamclmntgornry,

Patented Sept. 24, "1935 UNITED STATES PATENT OFFICE 2,015,531 ROLLCOATING MACHINE Application July as, 1932, Serial No. 624,589

5 Claims. (Cl. 91- 48) This invention relates to roll coating machines;and it comprises certain improvements in types of roll coaters adaptedto apply in one operation a smooth uniform layer of coating material toa 5 traveling web of paper, and having two cooperating rolls providedwith end dams adapted to retain a pool of liquid coating compositionbe-- tween their upper adjacent quadrants, one roll serving to carry amoving web of paper downward through the pool and the other doctor rolldriven in the same angular direction as the carrying roll serving toremove the excess coating composition from the paper, said improvementbeing in means for maintaining a clean surface on the 15 carrying rolland comprising a liquid receiving pan into which the lower part of theroll extends and a wiper located between the pan and the web carryingsurface, said wiper comprising a blade, advantageously of rubber,bearing on the carrying roll, a swinging clamp holding the blade,adjustable means causing the blade to bear with any' desired pressure onpoints along the roll and to permit it to be swung clear of the rollwhen desired; all as more fully hereinafter set forth 25 and as claimed.

In the field of making coated paper for fine printing purposes, Bradnerin U. S. Patent 1,838,358 has described a process of coating paper inwhich a web of paper passes partly around a 30 carrying roll which is ata small predetermined distance from another roll (doctor roll) whichrotates in the same angular direction as the carrying roll and at adefinite speed relative to the carrying roll. A pool of aqueous coatingcom- 35 position, (e. g., clay and casein mixture) through which thepaper passes is maintained between the doctor roll and the carrying rollby means of end dams, the excess coating material being removed by thedoctor roll.

40 When this machine is operated in accordance with the method.described in said patent, an

' unusually good coating job is obtained, the resulting coated paperrepresenting a decided improvement in the paper coating art. However,mill 45 operation of this machine has revealed dimculties when differingwidths of web are used and when certain defects in the paper stock areencountered. For example, when the paper stock contains a hole, such as,for example, a slime hole, coating 50 composition passes through thehole and fouls the carrying roll. This portion of coating composition iseither transferred to the back of the web or dries out upon the carryingroll. In the latter case the hump or spot of dried coating raisessubsequently passing paper at this point and 5 causes a light spot onthe coated paper due to insuflicient weight of coating at this point. Ineither case defective paper results.

Also there are inevitable small sidewise movements of the web from timeto time; weaving of the paper back and forth. Under these conditionscoating may smear the back of the paper along the edges, or may dry onthe carrying roll along the edges, producing a defective edge on thepaper. This is particularly troublesome in splicing from one roll ofpaper to another as it is practically impossible to align successiverolls of paper sufliciently exactly. This difficulty is especiallypronounced in going from a narrow web to a wider one. Also when thepaper breaks, the carrying roll becomes covered with coating and it isnecessary to wash this coating off and dry the roll before rethreading.

The object of the present invention is to provide apparatus to keep thesurface of the carrying roll clean and thereby avoid and overcomedefects in coating due to holes in the paper web, and the edge and otherdifliculties above mentioned; and this object is achieved in theapparatus hereinafter described.

According to the present invention, provision is made to wet thecarrying rollacross its entire length below the web engaging surface,and then to wipe the roll clean at a point in advance of the place wherethe oncoming web contacts with the roll. To accomplish this, a pancontaining a liquid, which is advantageously coating composition, ismounted just below the carrying roll and receives its lower periphery.Above the pool of liquid in the pan is mounted a special wiper engagingthe roll and ensuring a clean surface at the time the web makes contact.In its best embodiment this wiper carries a blade of fairly soft rubberengaging the surface of the roll throughout its entire length.

In' the accompanying illustration, I have shown the cleansing means ofthe present invention applied to a paper coater of the type 11-lustrated in the acknowledged Bradner Patent 1,838,358. In this showingFig. 1 is an end view, certain parts being shown in section;

Fig. 2 is a fragmentary plan view along line 2-2 of Fig. 1; and

Fig. 3 is a detail showing the wiper on an enlarged scale.

In the showing of Fig. 1, elements I and 2 are a pair of adjacent rolls,both indicated as turning in a clockwise direction. Diagrammatically'shown adjusting means 3 and 4 permit adjustment of the spacing betweenthe rolls. At each end of the roll assemblage are mounted stationarydams (see Fig. 2) 5 and 6. These dams together with the adjacent upperquadrants of the two rolls, define a trough containing a pool ofliquid 1. A traveling web of paper 8 coming from a stock roll of paper 9passes downwardly through the pool on carrier roll I and away to driers(not shown), passing a positioning idler roll ID. The liquid flows intothe pool and the excess coating is removed from the paper by the doctorroll 2. Liquid is supplied to the pool from a suitable source throughconduit II and a scraper It keeps the surface of the doctor roll clean.All these elements are substantially as shown in the acknowledgedBradner patent.

In the present invention, a shallow pan I3 is mounted just below thecarrying roll I. The idler roll in keeps the traveling web of paperclear of the upper edges of the pan, allowing this edge to be locatedjust below the point where the web leaves the roll. In this pan is showna body of coating composition l4. Excess liquid can be taken by overflowl5 and pumping means (not shown) back to conduit II. A rigid bar I'Ihaving trunnions I6 is carried in the bearings 22. The bar l'l carries ablade member l8 of rather soft vulcanized rubber. This blade is clampedin place by clamp IS. The bar I! is provided with handle 20 permittingthe wiper to be swung into and out of engagement with the roll. Lockingclamp 23 permits the blade l8 to be held firmly against the roll I. Inuse, the blade wears somewhat and it may be necessary to move it forwardto take up this wear. For this reason, the bar is provided with a seriesof screw adjusting means 2|, located at intervals along its length (seeFig. 2). By means of these adjust- .ing screws, local wear can becompensated for.

In starting up the apparatus under the present invention, the pan isfirst filled with coating composition. Care must be observed not to havethe rubber wiper blade in contact with the carrying roll until thecoating has wet the surface of the roll, as otherwise rapid wear on thewiper would result due to friction with a dry face. As soon assufficient coating is supplied to the pan l3 to wet the surface of roll.I, the wiper may be locked in place. The coating composition acts as anexcellent lubricant for the rubber wiper and the wiper does an excellentwiping job for long periods of time without any adjustment whatsoever. i

, spoilage of paper due to holes in the web is reduced to the singlesheet in which the hole exists, the wiper mechanism completelyeliminating any further spoilage from this cause. This lubricated wiperalso cleans the supporting roll from any wads of paper, dirt, etc.,which may accidentally be stuck upon the roll I. The edges of the paperare not contaminated with coating on the back nor is there any defect onthe edges on the coated side. Besides theiface of the carrying roll iskept clean and dry per- 5 mitting rapid threading of the paper.

Water alone may be used in place of coating composition in the pan, buton the whole, I find the use of the same coating composition as is beingapplied to the paper the most satisfactory. 10

Also the wiping edge may be of suitable metal, bakelite, etc., butrubber is better.

What I claim is: v

1. In a web coating machine, the combination with a doctor roll and acooperating web carrying roll and means for driving these rolls in thesame angular directions, of means for applying cleaning liquid acrossthe whole length of the carrying roll and means to remove substantiallyall of the liquid thus applied prior to contact with the web.

2. An improvement in paper coating machines in which a continuous web ofpaper is carried on a. rotating paper supporting roll and contacted witha body of fluid coating composition supported between said roll andanother rotating roll, said improvement comprising the combination ofsaid paper supporting roll with a container mounted below said roll andadapted to establish and maintain a liquid bath in contact with thelower periphery of said paper supporting roll and a wiper contactingwith said paper supporting roll above said liquid bath, the wiper beingadapted to clean off substantially all liquid from the roll prior to itscontact with the web.

3. An improved machine as set forth in claim 2 in which the wipingelement of said wiper is a rubber composition.

4. An improved wiper, suitable for use in the apparatus of claim 2, saidwiper comprising a rubber blade and a supporting frame, said rubberblade being firmly attached to said frame, said frame being adjustableto permit changing the position of said rubber blade, and means forlocally adjusting the rubber blade along its length.

5. The machine of claim 1 wherein the means for removing liquid from thecarrying roll comprises a wiping device, the active engaging surface ofwhich is rubber, mounted in an adjust- 5o able relation to the peripheryof said rotating roll, said wiping device comprising a bar mountedparallel to the axis of said roll and capable of rotating on its axis, arubber-blade adapted to press on the surface of the roll and a flexiblemetallic blade forming a backing for said rubber blade, said rubber andmetallic blades being detachably mounted on said bar with the metallicblade in contact therewith, by means of a clamp, a handle attached tosaid bar 30 for rotating said bar and lifting the rubber blade from theroll, means for locking said bar in a given position, and a series ofscrews carried on said bar, the ends r said screws contacting said metalblade, said screws serving to locally adjust 5 the position of saidrubber blade and the pres sure with which it bears on the surface of theroll.

WILLIAM J. MONTGOMERY.

